1. Technical Field
The present invention relates generally to structural monitoring technology, and more particularly to structural monitoring technology using motion capture.
2. Description of the Related Art
Construction structures are exposed to various loads, such as permanent load, wind load, seismic load, etc., in construction and usage stages. Accordingly, the evaluation of usability and structural health of structure is important procedure that must be performed in the structure design stage. If performance degrades in a structure due to large load, which has not been expected in a structure design stage, or deterioration, usability and structural health of the structure may be accompanied with much troubles.
To deal with this problem, Structural Health Monitoring (SHM) systems for evaluating usability and structural health of a structure in construction stage and usage stage have been proposed.
Structural monitoring may be classified into structural health monitoring and usability monitoring according to its purpose. Structural health monitoring is activity for monitoring the strain of a structure regarding, for example, the inclination of a building or the bending of columns, whereas usability monitoring is activity for monitoring the displacement of a structure regarding the residential sentiment of dwellers, such uneasiness about the vibration of a building due to wind.
Usually, strain gauges are used in structural health monitoring, whereas accelerometers or displacement meters are used in usability monitoring.
To evaluate the structural health of a structure, it is very important to estimate strain and stress observed at respective locations of the structure. In particular, the maximum stress should not exceed allowable stress suggested in the design standard.
Since it is difficult to measure stress at all the locations of a structure, strain and stress can be calculated by locating places with large stress via structural analysis, attaching strain sensors onto the places and then performing structural analysis based on measured values from the strain sensors.
However, in actual structures, due to inaccurate locations and magnitudes of load applied to the structures and uncertainty of support conditions of the structures, drawbacks, such as lack of confidence in the results of structural analysis and complication of wiring and limitation of measuring locations because sensors are connected with by cables.
The problem of sensors being connected with by cables can be overcome using image-based monitoring systems, such as laser systems, light detection and ranging (LIDAR) systems, or motion capture systems (MCS).
However, the problems of necessity of accurate load conditions and support conditions are common limitations of conventional structural monitoring researches.
As a result, there is still a need for structural monitoring methodology that can be applied to cases where load and support conditions are uncertain because it uses an image-based monitoring system but is not limited by load and support conditions.